1. Field of the Invention
The invention relates to a rotary electric machine rotor that includes a stacked body in which a plurality of steel plates are stacked together, and a plurality of magnets of which at least one is arranged in each magnet hole in the stacked body. More particularly, the invention relates to technology that reduces eddy current loss.
2. Description of Related Art
In a related rotary electric machine rotor, a structure that uses a rotor core that includes a stacked body of a plurality of steel plates is known. Also, a rotor with magnets in which magnet holes are formed through, in an axial direction, the stacked body in a plurality of locations in a circumferential direction, and magnets are arranged in these magnet holes, is also known.
Japanese Patent Application Publication No. 2013-165625 (JP 2013-165625 A) describes a structure of a rotary electric machine rotor having a plurality of magnets inserted into respective magnet holes, in which contact between two magnets is inhibited by resin being filled in between the magnets. The plurality of magnets contact the steel plates that form the rotor core, inside the magnet holes.
Japanese, Patent Application Publication No. 2010-141989 (JP 2010-141989 A) describes a structure of a rotary electric machine rotor having a plurality of magnets inserted into respective magnet holes, in which a resin foam sheet is arranged between the magnets, and the magnets are pushed against an inside surface of the magnet holes by thermal expansion of this sheet. The plurality of magnets contact the steel plates that form the rotor core, inside the magnet holes. JP 2010-141989 A also describes applying a surface coating to the magnets.
With the structure described in JP 2013-165625 A or JP 2010-141989 A, when forming the stacked body by stacking the plurality of holed steel plates in which holes have been formed by punching out insulation coated steel plates, adjacent holed steel plates contact each other via the insulation coating. In this case, adjacent holed steel plates are essentially not electrically connected together via connecting portions, but there is conduction between the holed steel plates and the magnets. Therefore, if eddy currents are generated in magnets that are adjacent in the circumferential direction, the eddy currents may short-circuit via the plurality of holed steel plates and become large, resulting in increased eddy current loss. Eddy current loss may be inhibited by inhibiting contact between the magnets and the steel plates by providing an insulation coating to the surface of the magnets by a coating forming process, but this would increase the cost of the magnets. Neither JP 2010-141989 A nor JP 2013-165625 A describes means for solving such a problem.